If I wanted to dabble in electronics just long enough to take two controllers and splice together their cables so that they act as one controller, where would I start?

My goal is that I have two controllers feeding into a single controller connector on a game system, and that pressing A on one controller is the same as pressing A on the other controller and so on. If one OR both are pressed it will look the same to the system.

I did a tiny bit of soldering when I was a kid, with kits that tell you exactly what component to put where. And I melted the plastic and the company sent me a replacement. So electronics is not a skill.

If you aren't used to soldering, i recommend you buy a bundle of through-hole resistors (cheap) and start practicing soldering them to a stripboard (also cheap). That will boost your confidence and make your hand sure.

Your soldering station normally comes with care and use instructions. My thumb of rule is the minimal amount of time to get the solder point properly wet. Keeping the tip of the iron slightly wet at all times helps. I remove excess solder and possibly slag from the tip on a moist sponge between soldering joints. Just feed a little more solder as you hold the tip to the hole. You want the ring of the hole to be a bit warmed up before you apply solder, so that it bonds. This takes just a fraction of a second, though.

At first I thought you meant making a 2 ports controller with lots of buttons that could work for specific homebrew games.Your idea is good. It would make something like this a lot easier https://www.youtube.com/watch?v=QkDjjyEY4UE

As for tools, you need:Soldering station (duh) - pick up one that lets you set the temperature. Solder with lead (more durable over time, easier to solder, but an environmental issue. shouldn't be used on things that go to recycling anytime soon, and isn't allowed in commercial products within the EU at least)good ventilationgood, ambient light to properly see what you're doing. a mat made of something that can take solder fleas and burn marks.

You might also want:wire stripper. tweezers and pliers.a copper wicker to desolder mistakes. I've found that the option (vacuum pumps) hardly work. Maybe i've tested a crap brand. But wickers are sure to fix it.

You'll probably need:Extra wire.

Before soldering wires to pins or points, strip about a centimeter or so of isolation. You can fold any excess of stripped wire. Roll the copper fibre between your fingers. Coat it with a thin layer of solder.

If a joint looks wrong, don't panic. Just put your tip there and resolder it. If the amount was wrong, apply more solder or draw excess solder away with a wicker.

It's good practice to be quick about soldering joints. If you're in contact for too long, you might damage the PCB and its traces. Chips may be sensitive to excessive heat, too. Discrete components like resistors can take a beating without failing, which is why they're good practice material.

NES and SNES controllers work by "freezing" the state of all buttons at the request of the software (this is why you strobe the controller register), and then feeding the "frozen" data to the software bit by bit. Having two NES controllers work the way you described will require you to use the 14021 chip of only one of the controllers, and connect the switches of both controllers to it in parallel. You're gonna need a different cable for the extra controller, since the normal cable doesn't have enough wires to transfer the state of all 8 buttons separately.

rainwarrior wrote:

By the way, on a Famicom you can just do this with expansion controllers

Yes, but as far as the hardware is concerned, the expansion controller is a separate device and its state is returned in a different bit, it's the software that ORs the states together.

NES and SNES controllers work by "freezing" the state of all buttons at the request of the software (this is why you strobe the controller register), and then feeding the "frozen" data to the software bit by bit. Having two NES controllers work the way you described will require you to use the 14021 chip of only one of the controllers, and connect the switches of both controllers to it in parallel. You're gonna need a different cable for the extra controller, since the normal cable doesn't have enough wires to transfer the state of all 8 buttons separately.

Couldn't you just split the strobe/clock outputs to both controllers, and simply OR the serial input?

(I think you should be able to do the whole thing externally without taking the controllers apart?)

The protocol is active low, so the correct chip to use would actually be an AND gate. Or a common anode diode configuration, perhaps with a pullup on the common side. Basically flip the diodes in FrankenGaphics' schematic and connect the resistor to +5V instead of ground.

Quick update. Wanted to share the final result here as GradualGames requested I make this for him.

I used a LS series AND gate which I deadbug soldered inside a little enclosure I stole from a cheapo USB hub. Added some stickers to cover up the 'TOMTOP' branding.

He requested one of these years ago from me for NES and I never got around to it. So I had the idea to make this work for both NES and SNES since SNES controllers are fully playable on a NES console. Has the added benefit of doubling as a SNES mouse to NES adapter at the same time!

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